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5101 (U3): Compressor temperature thermistor (TH4) open/short
Abnormal points and detection methods
TH4 is found to be open/short.
(The open/short detection is disabled for 10 minutes after
compressor starts, during defrosting operation, or for 10
minutes after returning from the defrosting operation. The
detection is also disabled when the outdoor temperature is
41°F (5°C) or less in cooling operation, and -4°F (-20°C) or
less in heating)
Open:
37.4°F (3°C) or less*
Short:
422.6°F (217°C) or more
TH4:
Thermistor <Compressor>
* -10°C [14°F] or less when PEFY-P·VMH(S)-E-F is connected.
Diagnosis of failure
Check the wiring and connector connection of
TH4.
Is there any abnormality such as
disconnection, looseness or break-
age?
Disconnect the connector to check the resis-
tance of TH4 using a multimeter.
Is the detected resistance normal?
Check the temperature of TH4.
Is the detected temperature normal?
OCH800A_59
<Detected in outdoor unit>
Yes
No
No
Yes
The detected temperature of TH4 can be displayed
by an operation of SW1 on the outdoor multi
controller circuit board.
SW1 Setting
ON
OFF
1 2 3 4 5 6 7 8
No
Yes
Causes and checkpoints
• Disconnection or contact failure of connectors
• Faulty thermistor
• Defective outdoor multi controller circuit board
The black square (■) indicates a switch position.
Connect the wiring/connector properly.
Replace the connector in the case of breakage.
Replace the thermistor.
Display on LED1,2
Unit
-99.9–999.9
°F
Replace the outdoor multi controller circuit board
(Malfunction of thermistor circuit).
No abnormality
(A connector contact failure is suspected.)
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